This invention relates to remote operating systems and, more particularly, to a system adapted for incorporation into a carrier vehicle and excavator combination which permits a worker in the cab of the excavator to remotely control the movement of the carrier vehicle on which the excavator is mounted for independent operation.
Heavy duty material handling equipment such as excavators having a large shovel at the distal end of a boom assembly are many times mounted for operation upon the back of a truck carrier. Both the truck carrier and the excavator have their own cabs in which workers are seated to independently operate the respective equipment. A worker drives the truck carrier over highway and individual job sites to position the excavator at the desired work location. With the truck carrier in place, either the same worker or a second worker proceeds to enter the excavator cab to operate the excavator which is rotatably mounted to the carrier through a center pin assembly.
Since it is often necessary to move the excavator about the job site via the truck carrier, different types of remote operating systems have been developed which permit the worker in the cab of the excavator to operate the truck carrier's movement, steering, braking, and throttle systems. This feature saves both time and money in that a second worker need not be available to enter the truck carrier cab to move it and the excavator. Also, if there isn't a second worker available, the first worker in the excavator cab need not exit his cab to enter the truck carrier cage to operate it.
The most favored remote operating system of the above type is one that is relatively simple in design and components to reduce the chance of breakdown, and one that may be incorporated into an existing carrier and excavator combination with a minimum of skill and effort. Many of the prior art remote control systems require a distinct power source and/or a series of complex (nd expensive) linkages between the excavator and carrier vehicle. For example, U.S. Pat. No. 3,599,814 issued to Brownfield on Aug. 17, 1971 discloses a remote operating system requiring an auxiliary engine mounted on the rotatable platform which operates the boom assembly. An auxiliary drive line interconnects the auxiliary engine to a fluid motor which is operable to transmit power from the auxiliary engine to the main drive line. The auxiliary drive line comprises fluid conduits which must be fed through the center pin assembly to deliver and recycle hydraulic fluid to and from the motor, respectively.
Other types of remote control systems which utilize hydraulic fluid traveling through conduits passing through the center pin assembly may be seen in U.S. Pat. No. 4,318,451 issued to Liggett on Mar. 9, 1982 and U.S. Pat. No. 2,959,260 issued to Johnson et al. on Nov. 8, 1960.
In U.S. Pat. No. 4,705,450 issued to Gano on Nov. 10, 1987, a hydraulic pump operates through a power take-off on the torque converter to provide fluid under pressure to a hydraulic drive motor which provides a secondary power input to the transmission. Fluid also travels via a second conduit through the center pin to provide hydraulic control for the upperstructure movable machinery components. While the Gano remote control system appears very useful for a carrier/excavator of the type not including a separate excavator engine, it would not be powerful enough to be installed upon the heavier carrier/excavators such as the GRADALL.RTM. 1000 series, for example. Furthermore, center pin assemblies which include means for the passage of fluid conduits therethrough are typically quite expensive.